But Parkinson’s also involves a variety of lesser-known . These may include:
-
mood changes
-
difficulties with memory and cognition (including slower thinking, challenges with planning or multitasking and difficulty paying attention or concentrating)
-
sleep disturbances
-
autonomic dysfunction (such as constipation, low blood pressure and urinary problems).
While these are sometimes referred to as the “invisible” symptoms of Parkinson’s, they often have a greater negative impact on than motor symptoms.
So, what does the new research tell us?
The study used data collected as part of the Australian Parkinson’s Genetics Study led by the QIMR Berghofer Medical Research Institute. After a pilot study in 2020, it was launched as an ongoing, nationwide research project in 2022.
Some 10,929 Australians with Parkinson’s were surveyed and provided saliva samples for genetic analysis. This is the largest Parkinson’s cohort studied in Australia and the largest active cohort worldwide.
There were several key initial findings.
1. Non-motor symptoms are common
The study reinforced how common non-motor symptoms are, with loss of smell (52 per cent), changes in memory (65 per cent), pain (66 per cent) and dizziness (66 per cent) all commonly reported.
Notably, 96 per cent of participants experienced sleep disturbances, such as insomnia and daytime sleepiness.
2. A better picture of risk factors
The study also provided insights into what can influence Parkinson’s risk.
This is important because we don’t completely understand what causes the dopamine producing cells in the substantia nigra to die in the first place.
is the primary risk factor for Parkinson’s. The new study found the average age for symptom onset was 64, and for diagnosis, 68.
3. Genes and environment both play a role
In the recent study, one in four people (25 per cent) had a family history of Parkinson’s. But only of Parkinson’s cases are caused by — or strongly linked to — mutations in specific .
It’s important to remember that families don’t only share genes but often their environment.
Multiple , such as pesticide exposure and traumatic brain injury, also increase risk of Parkinson’s.
The majority (85-90 per cent) of cases of Parkinson’s are likely due to between genetic and environmental risk factors, and advancing age.
The study showed environmental exposures linked to Parkinson’s risk were common:
-
36 per cent of people reported pesticide exposure
-
16 per cent had a prior history of traumatic brain injury
-
33 per cent had worked in high-risk occupations (such as agriculture, or petrochemicals or metal processing).
These exposures were significantly higher in men than in women.
4. Differences between the sexes
The disease is more common in men. In the new study, 63 per cent of those surveyed were male.
Parkinson’s also presents and progresses in males and females.
The study found women were younger than men at time of symptom onset (63.7 versus 64.4 years) and diagnosis (67.6 versus 68.1 years), and more likely than men to experience pain (70 per cent versus 63 per cent) and falls (45 per cent versus 41 per cent).
Men experienced more memory changes than women (67 per cent versus 61 per cent) and impulsive behaviours, particularly sexual behaviour (56 per cent versus 19 per cent) — although most participants exhibited no or only mild impulsivity.
What we still don’t know
The large-scale study and its comprehensive survey shed valuable light on people living with Parkinson’s in Australia.
But it’s still only a sliver of the population. More than 186,000 people with Parkinson’s were invited to participate and just under 11,000 took part — a less than 6 per cent response rate.
Of these participants, 93 per cent had European ancestry. So this sample may not be fully representative of Parkinson’s disease.
The information we have about symptoms also relied on self-reports by the study’s participants, which are subjective and can be biased or less reliable than objective measurements of function. To address this, the researchers are planning to use smartphones and wearable devices to collect more comprehensive data.
Finally, while this provides a snapshot of the current cohort, it’s not clear how participants compare to people of a similar age without Parkinson’s, or how their symptoms may change over time.
These are important areas of future research for this ongoing study.
What all this means
Studies like this provide crucial insights into risk factors linked to Parkinson’s. They also help us better understand the symptoms people experience.
This is important because the way Parkinson’s presents varies from person to person. Not everyone will experience the same symptoms to the same extent.
Similarly, the way the disease progresses over time differs between people.
A better understanding of the factors that influence this can lead to earlier identification of who’s at risk and more personalised ways of managing this disease.
